Ultra-low frequency high voltage generator 1 5 km explained
Using microcomputer control, voltage boost, step-down, measurement, protection are fully automated and fully electronic.
Output Frequency: 01hz、0.05hz、0.02hz
Reference standard: DL T8494-2004
Ultra-low frequency high voltage generator: VLF-80kV ultra-low frequency AC withstand voltage test device is a test equipment designed according to the new national industry test standard, which is safe and reliable, powerful, easy to use and simple to maintain. It is mainly used for various electrical products, electrical components, insulating materials, instrumentation, office equipment, etc. to carry out the dielectric strength test under the specified voltage to assess the insulation level of the product.
It is the preferred product for power operation related departments, electrical and electrical appliance manufacturing enterprises, metallurgy, coal mines, electrified railway related departments, scientific research units and colleges and universities that need withstand voltage test equipment to find the insulation defects of the tested product and measure the ability of overvoltage.
1. This test can be carried out during handover, overhaul, partial replacement of windings and routine tests. With 0The 1Hz ultra-low frequency withstand voltage test is carried out on the motor, and the defects of the insulation at the end of the generator are more effective than the power frequency withstand voltage test. The reason is that under the power frequency voltage, the capacitive current flowing from the wire rod causes a large voltage drop when it flows through the semiconductor halo layer outside the insulation, so that the voltage on the wire rod insulation at the end is reduced; In the case of ultra-low frequency, the current of this capacitor is greatly reduced, and the voltage drop on the anti-halo layer of the semiconductor is also greatly reduced, so the voltage on the end insulation is higher, which is easy to find defects.
2. Connection method: The test should be carried out in phases, the test phase should be pressurized, and the non-tested phase should be short-wired to the ground. This is shown in Figure 9.
3. According to the requirements of the relevant regulations, the peak value of the test voltage can be determined according to the following formula:
max＝√2βｋuo
where max : is 0Peak value (kV) of 1Hz test voltage
0.The equivalent coefficient of 1Hz and 50Hz voltage is taken as 12
Usually take 13∽1.5 Generally take 15
o: Rated voltage of generator stator winding (kv).
For example: the rated voltage is 13For 8 kV generators, the peak test voltage of ultra-low frequency is calculated as follows:
max＝ ×1.2×1.5×13.8≈35.1(kv)
4. The test time shall be carried out according to the relevant regulations.
5. In the process of withstand voltage, if there is no abnormal sound, smell, smoke and unstable data display, it can be considered that the insulation has withstood the test of the test. In order to get a better understanding of the insulation, the surface condition of the insulation should be monitored as comprehensively as possible, especially for air-cooled units. Experience has pointed out that visual monitoring can find abnormal insulation phenomena of generators that cannot be reflected by the instrument, such as surface corona, discharge, etc.
Ultra-low frequency withstand voltage test method for power capacitors.
The test operation method is similar to the above method, and the wiring method is shown in Figure 10. When determining the test voltage and test time, it should be done in accordance with the relevant regulations.
2. Output frequency: 01hz、0.05hz、0.02hz。
3. Load capacity: see Table 1
0.1 Hz extra large 11µf(
0.05 Hz Extra Large 22µf
0.02 Hz extra-large 55µf
4. Measurement accuracy: (3% full scale +0.)5kv）
5. Voltage waveform distortion: 5%.
6. Conditions of use: indoor, outdoor; Temperature: -10 +40 ; Humidity: 85%rh
7. Power supply: AC 50 Hz, 220V 5%.
8. Power fuse: see Table 1
Ultra-low frequency high-voltage generators are now used at home and abroad to modulate and demodulate the ultra-low frequency signal, so there is a sine wave waveform is not standard, the measurement error is large, the high-voltage part has spark discharge, the equipment is bulky, and the second and fourth quadrants of the sine wave also need high-power high-voltage resistance for discharge shaping, so the overall power consumption of the equipment is larger. This product can overcome some of these shortcomings.
There are many conventional aliases for ultra-low frequency high voltage generators in the ultra-low frequency high voltage generator industry, such as: ultra-low frequency withstand voltage tester, ultra-low frequency withstand voltage test device. Although the names are different, they are actually ultra-low frequency and high voltage generators, or take the ultra-low frequency high voltage generator as the core equipment, and cooperate with other components to carry out high voltage withstand voltage tests.
Ultra-low frequency high voltage generator VLF-30kV 40kv 50kv 60kv 80kv 0The 1Hz ultra-low frequency high voltage generator is suitable for: withstand voltage test of XLPE insulated power cable, withstand voltage test of hydroelectric generators and large generators.
Test principle of intelligent ultra-low frequency generator withstand voltage test device.
The ultra-low frequency insulation withstand voltage test is actually an alternative method for the power frequency withstand voltage test. We know that when performing power frequency withstand voltage tests on large generators, cables, and other specimens, a large capacity test transformer or resonant transformer is required because their insulation layer presents a large capacitance. Such huge equipment is not only bulky, expensive, but also very inconvenient to use. In order to solve this contradiction, the power sector has adopted a reduction in the frequency of the test, thereby reducing the capacity of the test power supply. It has been proved from many years of theory and practice at home and abroad that with 0The 1Hz ultra-low frequency withstand voltage test replaces the power frequency withstand voltage test, which can not only have the same equivalence, but also greatly reduce the volume and weight of the equipment, theoretically the capacity is about one of five hundredth of the power frequency, and the operation is simple, and the advantages are more than the power frequency test. This is why this approach is widely adopted in developed countries. The national government has formulated the "35kv and below XLPE insulated power cable ultra-low frequency (0.1Hz) Withstand Voltage Test Method" industry standard. China is promoting this method, and this instrument is developed according to this need of our country. It can be widely used in the AC withstand voltage test of cables and large high-voltage rotating machines.
3. Introduction to ultra-low frequency and high voltage generator products.
The ultra-low frequency and high voltage generator of this product is combined with modern digital frequency conversion advanced technology, using microcomputer control, and the voltage boost, voltage reduction, measurement, and protection are fully automated. Because it is fully electronic, it is small in size and light in weight, and the large-screen LCD display is clear and intuitive, and can display the output waveform and print the test report. The design index fully conforms to the power industry standard of "General Technical Conditions for Special Test Instruments for Power Equipment, Part 4: General Technical Conditions for Ultra-low Frequency and High Voltage Generators", and is very convenient to use. At present, mechanical methods are used at home and abroad to modulate and demodulate ultra-low frequency signals, so there are non-standard sine wave waveforms, large measurement errors, spark discharge in the high-voltage part, and the equipment is bulky, and the second and fourth quadrants of the sine wave also need high-power high-voltage resistance for discharge shaping, so the overall power consumption of the equipment is larger. This product can overcome some of these shortcomings and has the following characteristics:
1. The ultra-low frequency with a rated voltage less than or equal to 50kV adopts a single structure (one booster); The ultra-low frequency greater than 50kV adopts a series structure (two boosters are connected in series), which greatly reduces the overall weight and enhances the load capacity, and the two boosters can be used separately as the ultra-low frequency of the low voltage level.
2. The current, voltage, and waveform data are directly obtained from the high-voltage side sampling, so the data is accurate.
3. With over-voltage protection function, when the output exceeds the set voltage limit value, the instrument will stop for protection, and the action time is less than 20ms.
4. With over-current protection function: designed for high and low voltage double protection, the high-voltage side can be accurately shut down according to the set value; When the current on the low-voltage side exceeds the rated current, the machine will be shut down, and the operation time will be less than 20ms.
5. The high-voltage output protection resistor is designed in the booster body, so there is no need to connect the protection resistor outside.
6. Due to the use of high and low voltage closed-loop negative feedback control circuit, the output has no capacitance effect.
Fourth, technical parameters.
1.Output voltage rating: see Table 1
2.Output Frequency: 01hz、0.05hz、0.02hz
3.Load capacity: 01hz 1.1μf
0.05hz 2.2μf
0.02hz 5.5μf
4.Measurement accuracy: 3%.
5.Voltage positive and negative peak error: 3
6.Voltage waveform distortion: 5
7.Conditions of use: indoor, outdoor; Temperature: -10 +40 ; Humidity: 85%rh
The intelligent ultra-low frequency generator withstand voltage test device has the functions of power supply overcurrent, high voltage overcurrent, protection function, and the output voltage regulator cannot be started without returning to zero high voltage, which is a replacement product of traditional power frequency withstand voltage test equipment.